Another piece of research highlighting the issues with low vitamin D in the UK population - this time in the The Observer, Sunday 19th June, 2011.  While I agree wholeheartedly that a national campaign needs to get underway, I feel that this article focuses too much on diet and not enough on what I feel is the most obvious solution to the problem... sunshine.

Read the article and then my comments below:

Bad British diet is putting bones at risk of osteoporosis due to lack of vitamin D

Robin McKie, Science Editor - The Observer, Sunday 19th June, 2011.

My comments:

In over 2 years of introducing regular testing of vitamin D status to my clients, I rarely see a client within optimal range prior to supplementation - which illustrates what a significant issue vitamin D deficiency is in the UK.

Vitamin D is not only essential for bone health but also immune health, inflammatory conditions, cancer prevention, muscle pain, brain function and auto-immune conditions.

Is diet really the solution?

I find it interesting that this article focuses primarily on diet even though the recommendations of Appog included promotion of safe sunlight exposure.   Yes, food sources of vitamin D do exist but research is now showing that for optimal health we probably require more vitamin D than can be supplied from food alone.  Perhaps it is not so much our diet which is putting us at risk but our modern lifestyles, spent largely indoors, in cars and at desks during the middle of the day rather than outdoors, as previous generations would have done.  Prior to the agricultural and industrial revolutions, we primarily toiled on farms and as manual labourers. 

Have a look at this table below to compare the amount of vitamin D found in various foods with the amount of Vitamin D made by exposure to sunlight on the skin.

*It’s important to note that due to our latitude in the UK, we can only produce vitamin D naturally between the months of May – September – and even then, only when the sun is shining.  Anyone with dark skin, who covers up with clothing or wears sun cream is at risk of vitamin D deficiency.

Food, supplements or sunshine?

As a nutritional therapists, I will always recommend clients get nutrients from food wherever possible.  However, vitamin D is one exception to this rule. 

The best food source of vitamin D is oily fish but with mercury and PCB environmental pollution, women of child-bearing age are advised not to eat oily fish more than twice per week and for everyone else, increasing mercury intake is never going to be a good thing.  So in my mind, it is no longer viable to eat enough fish to supply adequate levels of vitamin D – even if there weren’t issues with toxins, remaining fish stocks are unlikely to cope with any major increase in consumption. 

I don’t see dairy as a solution either – vitamin D is a fat soluble vitamin, so only full fat milk contains a reasonable amount of D – even then, it is comparatively low.  Is it reasonable to expect everyone to drink litres of full-fat milk every day to reach their D quota?   Not to mention that some people are dairy-intolerant and around 95% of African, Asian and Native American people are genetically lactose intolerant.

Given the widespread deficiency there may be some role for fortification of foods with vitamin D -  but we evolved in the sunshine so why change now?

Sun exposure and cancer

Why has this article focused so much on diet rather than sunlight as a source of vitamin D?  It is likely to be a result of concerns about skin cancer risk. However, these concerns are starting to look outdated and possibly ill-informed.   Check out this blog and this site for more information about the benefits of vitamin D and safe sun exposure.

Research recently published in the BMJ found that malignant melanoma – the most life threatening of skin cancers – are just as frequently found on areas of the body not exposed to sunshine, illustrating that this form of skin cancer may not necessarily be linked to UV exposure.  Squamus and basal cell carcinoma are definitely associated to excessive sun exposure but these are non-aggressive cancers, they rarely spread are visible and can be dealt with effectively.

Given that vitamin D deficiency increases the risk of developing many other forms of cancer (which are often much harder to detect and treat than skin cancer), perhaps a little sun exposure is the lesser of two evils?   15 minutes 3 times a week for fair skinned individuals seems to be the easiest way to keep vitamin D levels topped up.  This with darker skin will usually need a little longer in the sunshine for the same effect.  Of course, if out in the sun for longer periods of time, 'sun-safe' principles apply - the goal isn't to tan or get sunburnt so put on a hat and sun cream to avoid skin damage after the initial 15 minutes. 

For those with dark skin or who keep covered for religious reasons, supplementation is relatively cheap but it is important that people don’t over-dose on vitamin D.  Supplementation should only be considered after seeking professional advise on dosage suited to your needs.  It is possible to take too much - for this reason, anyone who chooses to supplement should get their levels checked every 6 months.  For many, it may only be necessary to supplement during the winter months, when the sun is too low in the sky to provide enough UV light.

Personally, I feel that education around safe sun exposure is by far the most responsible and appropriate way to deal with vitamin D deficiency.  To top it off, it provides a great excuse for us all to take a 15 minute walk away from the desk during lunch break.  And that has got to be good for the mind, body and soul.

References:

Holick M. Deficiency of sunlight and vitamin D. BMJ 2008;336:1318-1319

Kennedy C, et al. The influence of painful sunburns and lifetime of sun exposure on the risk of actinic keratoses, seborrheic warts, melanocytic nevi, atypical nevi and skin cancer. J Invest Dermatol 2003;120:1087-93

Holick MF. Vitamin D deficiency. N Engl J Med 2007;357:266-81

Grant WB, et al. The association of solar ultraviolet B (UVB) with reducing risk of cancer: multifactorial ecologic analysis of geographic variation in age-adjusted cancer mortality rates. Anticancer Res 2006;26:2687-99

Moan J, et al. Addressing the health benefits and risks, involving vitamin D or skin cancer, of increased sun exposure. Proc Natl Acad Sci 2008;105:668-73